Interest rates on short-term Treasury bills rose in Monday’s auction to their highest levels in two months.

The Treasury Department auctioned $25 billion in three-month bills at a discount rate of 0.035 percent, up from 0.030 percent last week. Another $23 billion in six-month bills was auctioned at a discount rate of 0.055 percent, up from 0.050 percent last week.

The three-month rate was the highest since three-month bills averaged 0.045 percent on March 31. The six-month rate was the highest since those bills averaged 0.065 percent, also on March 31.

The discount rates reflect that the bills sell for less than face value. For a $10,000 bill, the three-month price was $9,999.12, while a six-month bill sold for $9,997.22. That would equal an annualized rate of 0.035 percent for the three-month bills and 0.056 percent for the six-month bills.

Separately, the Federal Reserve said Monday that the average yield for one-year Treasury bills, a popular index for making changes in adjustable rate mortgages, edged up to 0.10 percent last week from 0.09 percent the previous week.